不同柠檬酸类缓凝剂对水泥水化进程的影响及作用机制  

Effect of Citric Acid and Citrates on Hydration and Setting Performance of Cement

作　　者：李欢欢 卢子臣 尤紫阳 张立恒 孙振平[1,2] LI Huanhuan;LU Zichen;YOU Ziyang;ZHANG Liheng;SUN Zhenping(Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education,Tongji University,Shanghai 201804,China;School of Materials Science and Engineering,Tongji University,Shanghai 201804,China;Shanghai Urban Construction Material Co.,Ltd.,Shanghai 200438,China)

机构地区：[1]同济大学先进土木工程材料教育部重点实验室,上海201804 [2]同济大学材料科学与工程学院,上海201804 [3]上海城建物资有限公司,上海200438

出　　处：《硅酸盐学报》2025年第3期519-530,共12页Journal of The Chinese Ceramic Society

基　　金：国家自然基金(52208282);上海市科委(22dz1208904);上海市住建委(沪建科2022-002-031)资助项目。

摘　　要：由于水泥成分的复杂性及所用柠檬酸或盐种类的多样性,柠檬酸类缓凝剂的作用效果及作用机理仍未完全探明,本工作通过凝结时间和水化热等测试手段,系统评价了3种不同柠檬酸类缓凝剂(柠檬酸、柠檬酸钠与柠檬酸钾)在不同掺量及不同掺入方式时对无水石膏(AH)水泥及半水石膏(HH)水泥水化性能与凝结时间的影响,并通过吸附量、溶解速率测试等技术探究了其内在机理。结果表明:在AH水泥中,不论柠檬酸类缓凝剂种类及掺入方式,随着缓凝剂掺量的提高,均会引起水泥浆体先缓凝后速凝现象,而在HH水泥中此种高缓凝剂掺量下的异常快凝现象消失,说明水泥中HH的引入有助于解决柠檬酸类缓凝剂在高掺量下出现的异常凝结现象。此外,柠檬酸类缓凝剂的掺入方式也会极大改变其作用效果,相较于先把缓凝剂溶于水再与水泥混合的水掺方式,柠檬酸类缓凝剂先与水泥粉体混合的干掺方式显示出更强缓凝效果。除了吸附作用,柠檬酸类外加剂与钙离子的络合作用对水泥水化过程也起到重要影响。Introduction Retarders are necessary in construction projects such as long-distance transportation,high-temperature construction in summer and large-volume concrete construction.However,in practical applications,abnormal setting phenomena such as rapid or non-setting of concrete often occur due to the possibly incorrect or excessive mixing,which can affect the progress of the project and cause economic losses.It is thus of great significance for accurately regulating the setting and hardening properties of cement-based materials to clarify the cement hydration process and its mechanism under the action of retarders.Citric acid(CA)and its salts(mainly sodium citrate(SC)and potassium citrate(PC))are commonly used as retarders.However,there are still some controversies about their effect and mechanism in the existing studies.In this paper,CA,SC and PC with different dosages and addition methods were used to clarify the effect and mechanism of these retarders on cement hydration and solve the problem of abnormal setting during the use of such retarders.Their effects on the setting time of cement paste,hydration heat,and adsorption capacity under the action of different sulfate carriers(anhydrite(AH)and hemihydrate(HH))were investigated.In addition,the possible mechanism was also analyzed.Methods A fixed water-to-cement mass ratio of 0.4 was used.The dosage of citric acid and its salt was calculated based on a mass ratio of citrate to cement,and the dosage of citrate ion was 0.045%,0.090%,0.180%and 0.360%(mass fraction),respectively.Two addition methods were used,i.e.,W addition method and S addition method.For W addition method,the retarders were first dissolved in water and then mixed with cement.For S addition method,the retarders were first mixed with cement as a solid powder,and then the mixture was added to water.Two kinds of cement with different types of sulfate carriers were prepared,i.e.,AH-contained cement prepared with anhydrite and HH-contained cement prepared with hemihydrate.The setting time was measure

关 键 词：水泥水化 柠檬酸 缓凝剂 石膏 

分 类 号：TU528[建筑科学—建筑技术科学]